System for reducing silicon-consumption through selective deposition

Abstract

Disclosed is a system for fabricating a semiconductor device ( 100 ). A layer of cobalt ( 32 ) is deposited onto a silicon region ( 104, 106, 108 ) and annealed to form a cobalt silicide layer ( 118, 120, 122 ). Silicon layers ( 124, 126, 128 ) are selectively deposited onto the cobalt silicide layers ( 118, 120, 122 ). The semiconductor device ( 100 ) is annealed to form disilicide layers ( 130, 132, 134 ) from the cobalt silicide layers ( 118, 120, 122 ) and the silicon contained in silicon regions ( 104, 106, 108 ) and silicon layers ( 124, 126, 128 ).

What is claimed is:  
     
       1. A method of fabricating a semiconductor device, comprising the steps of: 
       depositing Co onto a first Si layer to form a Co layer;  
       thermal treating the above system to form a Co silicide layer;  
       removing an un-reacted portion of Co layer;  
       selectively depositing a second Si layer onto the Co silicide layer; and  
       annealing the Co silicide layer and the first and second silicon layers to form a cobalt disilicide layer.  
     
     
       2. The method of  claim 1  wherein the first Si layer comprises a gate region of a transistor. 
     
     
       3. The method of  claim 1  wherein the first Si layer comprises a source region of a transistor. 
     
     
       4. The method of  claim 1  wherein the first Si layer comprises a drain region of a transistor. 
     
     
       5. The method of  claim 1  wherein the step of selectively depositing the second Si layer comprises deposition by chemical vapor deposition. 
     
     
       6. The method of  claim 1  wherein the step of selectively depositing the second Si layer is performed at a temperature of in the range of 300-500° C. 
     
     
       7. The method of  claim 1  wherein the step of annealing the Co silicide layer and the first and second Si layers comprises annealing between about 600° C. and about 900° C. 
     
     
       8. A method of forming a semiconductor device comprising the steps of: 
       forming a gate on a substrate;  
       depositing a metal layer over the gate;  
       forming a self-aligning silicide and removing the residual metal;  
       selectively depositing silicon over the silicide layer; and  
       annealing the silicide on the gate.  
     
     
       9. The method of  claim 8 , wherein the step of depositing a metal layer over the gate comprises depositing a metal layer comprising cobalt. 
     
     
       10. The method of  claim 8 , wherein the step of annealing comprises annealing at a temperature in the range of 600 degrees Centigrade to 900 degrees Centigrade. 
     
     
       11. The method of  claim 10 , wherein the step of annealing comprises annealing for a time period in the range of 10 seconds to 100 seconds. 
     
     
       12. The method of  claim 8 , wherein the step of depositing a metal layer further comprises depositing a metal layer having a thickness in the range of 4 to 40 nanometers. 
     
     
       13. A method of forming a semiconductor device in the surface of a substrate, the method comprising the steps of: 
       separating a semiconductor gate body from the outer surface of the substrate by a gate insulator layer;  
       forming a conductive drain region in the outer surface of the substrate and spaced apart from the gate body;  
       forming a conductive source region in the outer surface of the substrate and spaced apart from the gate body opposite the conductive drain region to define a channel region in the substrate disposed inwardly from the gate body and the gate insulator layer;  
       depositing a metal layer over the gate body, the conductive source region, and the conductive drain region;  
       reacting the metal layer with the gate body, the conductive source region, and conductive drain region to form respective first, second and third silicide regions;  
       selectively removing unreacted metal layer from non-conductive regions;  
       selectively depositing silicon over the first, second and third silicide regions; and  
       reacting the silicon with the first, second and third silicide regions to form respective first, second and third disilicide regions.  
     
     
       14. The method of  claim 13 , wherein the step of depositing a metal layer over the gate body, the conductive source region, and the conductive drain region comprises depositing cobalt. 
     
     
       15. The method of  claim 13 , wherein the step of reacting the silicon with the first, second and third silicide regions comprises annealing the silicon and the first, second and third silicide regions. 
     
     
       16. The method of  claim 15 , wherein the step of annealing comprises annealing at a temperature in the range of 650 degrees Centigrade to 850 degrees Centigrade for a time period in the range of 10 seconds to 100 seconds. 
     
     
       17. The method of  claim 13 , wherein the step of depositing a metal layer further comprises depositing a metal layer having a thickness in the range of 4 to 40 nanometers.